Question

If an ELGamal cryptosystem in Z11 has private key 3 and ciphertext (5,6), then what is plaintext?

Answer 1

Answer:

Example. Bob's public key is the set (31, 3, 17). Bob then receives the pair r, t and decrypts the message as below. The exponent of 23 is used in decryption as this is equivalent to -z ≡ -7 ≡ 27 (mod 30).